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[Oroville Dam] Please Stop Raining
Aegis
Fear My DanceOvershot Toronto, Landed in OttawaRegistered User regular
Fear My DanceOvershot Toronto, Landed in OttawaRegistered User regular
(Helpful overview of the Dam and its geographic relation in Califnornia by Vox)
Oroville Dam is the tallest dam in the United States, measuring 770 ft tall (44 ft taller than the Hoover Dam) and containing a water supply (Lake Orville) of over 3.5 million acre-feet (4.4 km3). In addition to providing hydroelectric power, the resevoir of Lake Orville provides water for over 25 million people and is a key component of the Central Valley Project. Conceived of during the New Deal era, the CVP is a federal water management program to provide irrigation to California's Central Valley. The Dam itself was started in 1961 with work completing and the dam coming into operation in 1968.
Now, normal operation of the Oroville Dam includes the operation of a spillway, a mechanism by which water can be released from the resevoir to lower the level of the Dam and ensure it doesn't overfill during periods of lots of precipitation. This is what the spillway should look like when in operation:
This, meanwhile, is the current state of the spillway (as of Friday or this weekend):
There should not be a gigantic sinkhole there.
However, the Dam does have a backup plan in case the main spillway has a problem. That would be the Emergency Spillway, which is basically a fancy way of saying "letting the Dam overflow a part a little ways up from the regular spillway and flow down the hillside until it eventually hits the Feather River." For the first time in the history of the Oroville Dam, the California Department of Water Resources used the Emergency Spillway this weekend:
https://www.youtube.com/watch?v=fA52L0eabNoUnfortunately, they put a stop to this not long after using it. Turns out, there were concerns regarding erosion at the base of the earth near the Emergency Spillway and they did not want to run the risk that the retaining wall that makes up said Emergency Spillway would erode and collapse, releasing a metric fuckton of water at once down the hill. Because of this new problem to an already serious issue facing the main Spillway, an evacuation order was issued for 188,000 people downstream:
Immediate evacuation from the low levels of Oroville areas downstream is ordered. From Oroville to Gridley...low level areas around the feather river will experience rapid river rises.This is not a Drill. This is not a Drill. Repeat this is not a drill................Move to higher ground now. Act quickly to protect your life.
As of Monday's press conference, this evacuation order is still in effect and with rain still projected for the coming week, it's unknown as of yet when they can return.
This would all be problematic, and not necessarily be a crisis, except for the fact that it will not stop raining in California. Here are the current resevoir levels throughout California:
So, Lake Orville's been sitting at 150% of historical average and bobbing between 95 and 101% capacity. Current weather expectations for the upcoming week: more rain. What this means for the situation is that notwithstanding said hole in the spillway, the Dam itself can't not run water down the spillway. Officials need to run water down the damaged spillway in order to reduce the Lake's current capacity not only because it is historically overfull, but also to make room for future rain that just won't stop falling. This, naturally makes the sinkhole problem worse, as water continues to extend the size of the hole (which when it first appeared, only covered half of the spillway and not an entire chunk as well as half the hill on either side that you see in the picture above). Edit: Here's a nice side-by-side comparison of what's happening as they have to run water over it:
In terms of what could be done, the press conference that was held today (an update on the evacuation and the current status of the Dam and situation in general) had multiple reporters asking questions of whether officials knew about a 2005 request by environmental groups, including the Sierra Club, that suggested the spillway be armoured with Concrete over fears of its integrity. Given the current massive sinkhole spreading across the spillway, expect to hear more of this report as the crisis develops, and in general of the potential problems with critical infrastructure this old not receiving sufficient maintenance attention.
Useful articles on the matter:
http://www.vox.com/science-and-health/2017/2/13/14598042/oroville-dam-flood-evacuation
http://www.forbes.com/sites/marshallshepherd/2017/02/13/the-science-behind-why-the-u-ss-tallest-dam-is-causing-major-evacuations/#665d24d54fac
We'll see how long this blog lasts
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Currently DMing: None
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[5e] Dural Melairkyn - AC 18 | HP 40 | Melee +5/1d8+3 | Spell +4/DC 12
Aegis on
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https://www.reddit.com/live/yfixu0gbq4ub/
Yesterday's 10 day precipitation model starting Thursday.
Haven't read the details yet, but this thread has impressive pictures of the erosion.
"Waaaaahhhhhhhh please stop raining!"
You Californians are never happy.
(I'm kidding BTW, I lost most of my childhood to the Tuolumne River flood in 1997. I know how awful they can be.)
the "no true scotch man" fallacy.
Northern California has its own issues, but I really hope they devote some funds to an area other than Sacramento, San Francisco and LA sometime for infrastructure.
Edit: There have been a handful of floods in my lifetime in the area. People always laugh about how the stupid Californians always have a drought and then mudslides and apocalypse stage rains. The state is very large and while central and southern California need the water, the north and mountain range areas are the places that have to deal with all of the storage and capture of that water. The reservoirs can only capture and hold so much water at a time. Lake Shasta still looks (as of a few months ago) like a mud puddle, just because torrential rains fall and destroy things every few years, doesn't mean that the Sacramento River and Los Angeles County wont be in a drought again in a year.
They've been talking about investing in the states ability to capture and maintain water stores since I was a little kid. I guess water isn't a sexy thing to spend money on?
Influx into the resevoir (Feb 9th): 130,000 cfps (cubic feet per second)
When the spillway failed and the hole appeared: 50,000 cfps (outflow)
When they were running the spillway even with the hole: ~100,000 cfps
The press conference today noted that at one point they were running the spillway at 150,000 cfps to bring the 130,000 cfps influx under control (it's dropped from that to 80,000), and that the maximum design for the spillway was around 160,000 cfps. I believe since this past weekend, influx has calmed down slightly (until it rains starting Wednesday), but this is the issue they're facing: there's too much water coming into the resevoir and now they really don't want to run the Spillway at remotely close to what they need to because it's making that hole problem so much worse.
Edit: The hydroelectric plant and the "fish bypass" also collectively add another ~20,000 cfps outflow.
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[5e] Dural Melairkyn - AC 18 | HP 40 | Melee +5/1d8+3 | Spell +4/DC 12
Kind of.
The problem is three-fold, and it's really mostly #3:
1) Northern California finally got a good rainy season! Yay!
2) The main spillway (which is where excess water gets routed) developed a crater. Boo! Well, these things happen, which is why we have an auxiliary spillway...
3)... but in this case, not only has the auxiliary spillway never been used before in the entire history of the dam, but it's barely been inspected. So now the auxiliary spillway has failed, largely due to neglect.
the "no true scotch man" fallacy.
Someone passed California that fucking monkey's paw that's been going around.
Just under half the population of all of Wyoming lives in one small county in California. This is a big deal.
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It won't be. :-(
Trump said he wanted to be all about infrastructure projects!
Buuuut then he found out that infrastructure projects cost money...
Rock Band DLC | GW:OttW - arrcd | WLD - Thortar
Infrastructure never is
I feel like if you built the whole dam in 7 years, a hole ought not take all that long.
I can only guess, but they've been forced to use the spillway even with the hole in it because it was the only way to prevent failure of the dam. This isn't a long running problem that has been ignored, it's an... oh wow, there's suddenly a sinkhole in the middle of our dam spillway where there wasn't one before.
I mean yes, it's probably a larger issue of being ignored and neglected over the past 20 years, but that's something every piece of our infrastructure is seeing.
Someone on a comment thread somewhere said that that spot on the main spillway had been patched up a bit several years ago, but the underlying problem was probably serious enough that they needed to do a major replacement instead of what they did.
They can't exactly fix it now, as they have too much water in the reservoir that needs to be drained in the short term and the rainy season isn't over yet. This went to full on crisis pretty quickly with the massive amount of rain that region of California has gotten recently.
For a comparison, the construction of a spillway for the Folsom Dam cost between $900 million and $1 billion, for a modern spillway with twice as much outflow capacity.
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[5e] Dural Melairkyn - AC 18 | HP 40 | Melee +5/1d8+3 | Spell +4/DC 12
As to spool32's question, the hole on the main spillway literally appeared within the last week (or so), but as mentioned above they've kept running the main spillway to keep the lake down. Now that there are erosion concerns on the alternative spillway they want to try and drop the lake like 50 feet before the next storms (Wednesday night), so there's been literally no time to fix the main spillway problem. They can work on the emergency spillway right now (current plan: helicopter giant bags of rocks to fill the erosion holes) but even though it's sunny they can't stop water going down the regular spillway if they want to make room in the lake.
The hole on the main spillway also has been growing, although water's been running clear for a while from what I've seen, meaning most of the erosion of the surrounding hills just around the spillway already hit bedrock.
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[5e] Dural Melairkyn - AC 18 | HP 40 | Melee +5/1d8+3 | Spell +4/DC 12
So, as long as they prevent any further erosion and/or reinforce things on the emergency spillway side then you won't have catastrophic failure. Still have the issue on the main spillway which will need to be addressed but that's not a catastrophic failure level.
As things stand right now, the dam itself isn't in danger. If the emergency spillway breaches, my understanding is that it would be ~30 feet of water (which is a ton, but small potatoes compared to the rest).
Obviously at the rate of erosion they saw yesterday they thought it was eroding enough to possibly fail "within the hour." A later press conference said it appeared to begin eroding at a slower rate than earlier. With the water not spilling over right now they can see how much erosion they really suffered and how much support they think they currently have, or can add. But we're not going to get that info. For now evacuation is still in effect so they feel there's still a risk of failure.
https://www.metabunk.org/oroville-dam-spillway-failure.t8381/page-6
The water flow is strong enough to tear quite a bit of that hillside down to bare bedrock. Aside from dropping in the boulders like they are doing for the emergency spillway, I'm not sure how much they can do until they get enough of a breather from the weather to start rebuilding the thing.
https://www.google.com/amp/www.sfgate.com/news/amp/Biggest-dam-failures-in-U-S-history-10928774.php?client=ms-android-hms-tmobile-us
Looks like 1972 was a surprise twofer, otherwise it mostly seems to be the late 1800s or early 1900s
Edit: Also, first hit on my search was from RT, with video, so good to see the motherland is taking notice
It's 1.25 Megaliters, roughly.
Going to blow your mind right now.
Half the state is still in a drought. Like literal "water on the ground" drought, not the long-term "depleted aquifer" drought (which, frankly, the whole state probably still is).
Why can't they just send water down the spillway with the sinkhole in it? Won't the water just fill the sinkhole and then continue down the spillway as normal?
They are. that is why the hole is getting bigger. The 100,000 cubit feet of water they're running down the spillway per second is eroding the dirt on it.
If it erodes too much, there might not be enough dirt holding the lake up, and then the dam (effectively) fails.
Current worst case scenario is that the main spillway deteriorates to an unusable state, forcing use of the emergency overflow which is uncontrolled and untested.
This weekend that occurred and alarming erosion of that structure was observed, suggesting that the aux spillway could fail. That structure has a height of 30ft (assuming it just vanished). More likely some cross section fails and uncontrolled releases in the millions of cfs occur. Levees downstream probably would not be able to cope with that release.
Which is very bad, but not the nightmare of the main dam failing.
Same, and I use that weirdo system every day.
I'm also going to be worried about the general stability of the dam itself because at the moment everything surrounding the dam seems to have a problem or two and generally these sorts of problems don't just spring up out of nowhere. If everything really -does- go tits up and the auxiliary spillway fails there's no telling what -that- does to the structure of the main dam itself.
The spillways have heights of somewhere in the range of 770 feet. They have to by mathematical necessity because they must connect the overflow point (somewhere around the top of the dam) to the outflow river (at the bottom). (Unless the outflow river flows about 740 feet up hill)
The immediate portion of the spillway at the top is only 30 feet. But if that goes the same process that caused it to fail is now acting on the immediate portion below it; except uncontrolled and with millions of gallons of water running over it at high speed.
To wit; the spillway doesn't just "become unusable" it becomes unusable because the hill on which it resides begins to fail from the water flow.
It's almost like upfront infrastructure maintenance spending saves money by preventing the likelihood of catastrophes like an overflowing dam wiping out a dense residential town and causing hundreds of millions in damage and lost property on top of astronomical repair costs
Anyway I heard on NPR that environmental groups had raised concerns about the emergency spillway in 2005. I assume it is routine to ignore environmental groups, but did they actually identify the problem and in the intervening 12 years was any effort made at all to even bother checking it now out? What authority is in charge of maintaining/repairing this kind of infrastructure?
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